Flexible packaging structure with a built-in opening and reclose feature

ABSTRACT

A flexible packaging laminate is formed to have a built-in opening and reclose feature by forming the laminate as a two-part structure having an outer structure joined in face-to-face relation with an inner structure. Score lines are formed in both structures to enable an opening to be formed through the laminate by lifting an opening portion (e.g., a flap or the like) of the two structures out of the plane of the laminate. The score line through the outer structure defines a larger opening than the score line through the inner structure, such that a marginal region of the outer structure extends beyond the edge of the opening portion of the inner structure. A pressure-sensitive adhesive is used to re-adhere the marginal region to an underlying surface of the inner structure adjacent the opening through the laminate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of currently pending U.S. applicationSer. No. 13/542,998, filed on Jul. 6, 2012, which is a continuation ofU.S. application Ser. No. 13/031,469, filed on Feb. 21, 2011, now issuedas U.S. Pat. No. 8,262,832, which is a divisional of U.S. applicationSer. No. 12/556,292, filed on Sep. 9, 2009, now issued as U.S. Pat. No.8,262,830, which is a divisional of U.S. application Ser. No.11/098,872, filed on Apr. 5, 2005, now issued as U.S. Pat. No.7,717,620. The entire disclosures of each of the above are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to flexible packaging for products, andparticularly relates to methods for making such packaging that isreclosable after initial opening.

A variety of food and non-food products are packaged using flexiblepackaging materials formed primarily of laminations of one or more ofpolymer films, metallized polymer films, paper, metal foil, and thelike. In many instances, packages contain products that may be used orconsumed a little at a time, and the products may be susceptible tobeing adversely affected (e.g., becoming soggy, drying out, etc.) byexposure to the surrounding environment. Accordingly, there isfrequently a desire to be able to reclose a package after its initialopening to keep product that remains in the package fresh.

Various opening and reclose arrangements have been developed forflexible packaging. Often, reclosability is achieved by using apressure-sensitive adhesive label that is attached to the exterior ofthe package adjacent the location where the package is opened. Suchlabels are formed separately from the packaging structure itself and areadded to the packaging structure. The labels thus represent additionalexpense. Furthermore, it is often necessary to ship a roll of thepackaging material to a converter for application of the labels, afterwhich the roll is shipped back to the packager for manufacture of thepackages. This manufacturing process is inefficient. The use of labelsalso entails waste in that it is typically necessary to employ a releaseliner with the labels, which liner is removed and discarded. The labelsare usually die cut from a web of material, and the skeleton left overafter the die-cutting operation is also wasted.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the above needs and achieves otheradvantages, by providing a flexible packaging structure and method formaking same, in which the structure has a built-in opening and reclosefeature that does not require a separate label. In accordance with oneaspect of the invention, a flexible packaging structure is formed tohave a built-in opening and reclose feature by forming the packagingstructure as a two-part structure, having an outer structure joined inface-to-face relation with an inner structure. Each of the outer andinner structures can comprise one or more layers of flexible packagingmaterial such as polymer film, paper, metal foil, and the like. An outerline of weakness is formed in the outer structure to define an outeropening portion that can be lifted out of the plane of the outerstructure. Similarly, an inner line of weakness is formed in the innerstructure to define an inner opening portion that can be lifted out ofthe plane of the inner structure. The outer and inner opening portionsare attached to each other such that the outer and inner openingportions can be lifted out of the plane as a unit, thereby creating anopening through the packaging structure defined by the inner line ofweakness.

The outer opening portion is larger in area than the inner openingportion and has a marginal region that extends beyond the peripheraledge of the inner opening portion. When the outer and inner openingportions are lifted out of the plane to create the opening, anunderlying portion of the inner structure in registration with themarginal region of the outer opening portion is exposed adjacent theopening. A pressure-sensitive adhesive is applied to either the marginalregion of the outer opening portion or the underlying portion of theinner structure. Therefore, after initial lifting of the outer and inneropening portions, the opening through the structure can be reclosed byadhering the marginal region of the outer opening portion to theunderlying portion of the inner structure via the pressure-sensitiveadhesive.

In accordance with one embodiment of the invention, thepressure-sensitive adhesive is onto one surface of the outer structure,the pressure-sensitive adhesive forming a strip having an outerperimeter and an inner perimeter, and a permanent laminating adhesive ispattern-applied onto the one surface of the outer structure such thatthe permanent adhesive does not cover the strip of pressure-sensitiveadhesive. Next, the outer structure is adhesively joined to the innerstructure via the permanent adhesive so as to form a laminate. The outerstructure and inner structure in preferred embodiments are coextensivewith each other, and advantageously are each continuous webs drawn fromrespective supply rolls and laminated together to form a laminate thatis a continuous web.

The laminate is then advanced to a scoring station at which an outerline of weakness (also referred to herein as a “score line”) is formedthrough the thickness of the outer structure, and an inner score line isformed through the thickness of the inner structure. Advantageously,each of the score lines is registered with respect to the strip ofpressure-sensitive adhesive such that neither score line is locatedwhere there is permanent laminating adhesive between the outer and innerstructures. The outer score line delineates the outer opening portion ofthe outer structure that is separable from the outer structure along theouter score line, and the inner score line delineates the inner openingportion of the inner structure that is affixed to the outer openingportion by the permanent adhesive and is separable from the innerstructure along the inner score line.

It is also within the scope of the invention to use onlypressure-sensitive adhesive, with no permanent laminating adhesive. Inthis case, the pressure-sensitive adhesive serves to join the outerstructure to the inner structure over their entire surfaces.

The score lines can be formed by laser scoring or by mechanical scoringor cutting such as by die cutting or kiss cutting or the like. Theadhesive(s) can be applied to the outer structure as noted, butalternatively can be applied to the inner structure. The adhesive(s) canbe applied using any suitable equipment and technique, such as by agravure roll or the like.

The pressure-sensitive adhesive can be applied such that there is aregion that is free of the adhesive to form a thumb tab or graspingportion of the opening portion that can be readily grasped and pulledback to initiate opening.

The outer line of weakness or score line preferably penetrates throughthe thickness of the outer structure but not through the innerstructure. Similarly, the inner score line preferably penetrates throughthe thickness of the inner structure but not through the outerstructure.

The inner structure of the laminate advantageously includes a sealantlayer forming the inner surface of the laminate. The sealant layer cancomprise a heat seal material such as polyethylene, polypropylene,ionomer resin such as SURLYN®, or the like, or a cold seal material. Theheat seal or cold seal layer can comprise either a film or a coating.The inner structure advantageously also includes a barrier layerproviding a barrier against the passage of moisture and/or oxygen. Insome applications such as the packaging of moisture-sensitive products(e.g., cookies or similar products that tend to be degraded when exposedto the environment), it is important to provide a moisture barrier. Thebarrier layer can comprise any of various polymer-based barriermaterials including barrier polymer films such as ethylene vinyl alcoholcopolymer (EVOH), polyamide, and the like; metallized polyolefin filmssuch as polyethylene, polypropylene, oriented polypropylene, and thelike; AlOx-coated polymer films; SiOx-coated polymer films; metal foilsuch as aluminum foil; and others. Although the term “barrier layer” isused in connection with metallized films to refer to the entiremetallized film, it will be recognized that it is the layer of metalthat provides the barrier function. Likewise, it is the AlOx or SiOxcoating that provides the barrier function in the ceramic-coated films,but the entire film nevertheless is referred to herein as a “barrierlayer”.

The outer structure advantageously includes a layer of polyester such aspolyethylene terephthalate, which has a desirable crisp feel and isreadily printed. The polyester layer can be printed with inks to providegraphics and indicia. In preferred embodiments, the polyester layer istransparent and is reverse-printed on the surface that faces the innerstructure.

The process in accordance with the invention comprises an in-lineprocess wherein the opening and reclose features are formed in thepackaging laminate during the production of the laminate. Accordingly,it is not necessary to ship the laminate to a converter for applicationof labels or the like. Thus, the waste and the various material andshipping expenses associated with the use of separate labels areavoided.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is a diagrammatic depiction of a first phase of a manufacturingmethod for making a flexible packaging structure in accordance with oneembodiment of the invention;

FIG. 1a is a view of the first structure along line 1 a-1 a in FIG. 1;

FIG. 1b is a view of the first structure along line 1 b-1 b in FIG. 1;

FIG. 2 is a diagrammatic depiction of a second phase of the method inaccordance with one embodiment of the invention;

FIG. 3 is a diagrammatic depiction of a second phase of the method inaccordance with another embodiment of the invention;

FIG. 4 is a perspective view of a package that can be formed from aflexible packaging structure made in accordance with the method of theinvention;

FIG. 5 shows the package of FIG. 4 after being opened;

FIG. 6 is a cross-sectional view along line 6-6 in FIG. 4;

FIG. 7 is a cross-sectional view along line 7-7 in FIG. 5;

FIG. 8 is a perspective view of another type of package that can beformed from a flexible packaging structure made in accordance with themethod of the invention; and

FIG. 9 shows yet another type of package in accordance with theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present inventions now will be described more fully hereinafter withreference to the accompanying drawings, in which some but not allembodiments of the invention are shown. Indeed, these inventions may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

As an initial overview of preferred embodiments of the invention, aflexible packaging laminate is constructed to have a built-in openingand reclose function. The laminate is constructed as a multi-layerstructure by adhesively laminating a first structure to a secondstructure, wherein each of the first and second structures comprises oneor more layers of flexible material(s). Permanent and pressure-sensitiveadhesives are applied to one of the structures in predeterminedpatterns. Once the laminate is formed in this manner, scoring operationsare performed on both sides of the laminate in registration with theadhesive patterns, but each scoring operation penetrates only through apart of the thickness of the laminate; in particular, a scoringoperation performed on the side of the laminate adjacent the firststructure results in penetration through the first structure, butwithout complete penetration through the second structure, andpreferably without any substantial penetration, and more preferablywithout any penetration, into the second structure. Likewise, thescoring operation performed on the side of the laminate adjacent thesecond structure results in penetration through the second structure,but without complete penetration through the first structure, andpreferably without any substantial penetration, and more preferablywithout any penetration, into the first structure.

More particularly, with reference to FIG. 1, a first phase of themanufacturing process is depicted. A first structure 10 is advanced froma supply roll 12 by suitable web driving and handling equipment (notshown) to an optional print station 14 comprising a printing apparatus,such as a rotogravure printer or the like, for printing graphics and/orindicia on the first structure by applying inks to a surface of thefirst structure. The first structure 10 comprises one or more layers offlexible packaging material. Various materials can be used for thelayer(s) of the first structure, including polymers such polyesters,polyolefins (including homopolymers and copolymers), polyamides, andothers; paper; metal foil; and the like. In a preferred embodiment ofthe invention, the first structure 10 includes an outer layer that issubstantially transparent and is reverse-printed in the print station14, i.e., the inks are applied to the surface of the first structure 10that is subsequently laminated to another structure, as described below;from the opposite side of the first structure, which will form anexterior of a package constructed from the packaging laminate, the inksare visible through the first structure. As an example, the firststructure 10 can comprise a layer of polyester such as polyethyleneterephthalate or the like.

Prior to printing the first structure in the print station, the surfaceof the first structure that is subsequently laminated to the otherstructure can be treated by a corona discharge or flame treatmentapparatus 16 to render the surface more-receptive to the inks and/or torender the surface more-readily bondable to the pressure-sensitiveadhesive that is subsequently pattern-applied to the surface asdescribed below. Alternatively, the first structure 10 can have alreadybeen so treated prior to being wound into the supply roll 12, such thatthe treatment apparatus 16 is unnecessary.

Following the optional corona/flame treatment and/or optional printingoperation, and with reference to FIGS. 1 and la, the first structure 10is advanced to a first adhesive application station 18 at which apressure-sensitive adhesive 20 is applied to the first structure in apredetermined pattern 22 that recurs at regular intervals along thelengthwise direction of the first structure. The predetermined pattern22 is generally in the form of a strip of various forms or shapes. Asillustrated, a preferred shape for the strip pattern 22 is generallyU-shaped, for reasons that will become apparent in the description ofFIGS. 4-8; however, other shapes for the pattern 22 can be used, theinvention not being limited to any particular pattern. The pattern caninclude a region 23 that is free of adhesive and will ultimately form athumb tab or grasping portion of the first structure 10 as furtherdescribed below.

The pressure-sensitive adhesive 20 can comprise various compositions.Pressure-sensitive adhesives form viscoelastic bonds that areaggressively and permanently tacky, adhere without the need of more thana finger or hand pressure, and require no activation by water, solventor heat. Pressure-sensitive adhesives are often based on non-crosslinkedrubber adhesives in a latex emulsion or solvent-borne form, or cancomprise acrylic and methacrylate adhesives, styrene copolymers(SIS/SBS), and silicones. Acrylic adhesives are known for excellentenvironmental resistance and fast-setting time when compared with otherresin systems. Acrylic pressure-sensitive adhesives often use anacrylate system. Natural rubber, synthetic rubber or elastomer sealantsand adhesives can be based on a variety of systems such as silicone,polyurethane, chloroprene, butyl, polybutadiene, isoprene, or neoprene.When the packaging laminate of the invention is to be used for foodpackaging, the pressure-sensitive adhesive generally must be afood-grade composition. Various pressure-sensitive adhesives areapproved by the U.S. Food and Drug Administration for use in direct foodcontact, as regulated by 21 CFR Part 175.300. A preferred food-gradepressure-sensitive adhesive for use in the present invention is Jonbond743 available from Bostik Findley. Additives (e.g., particulates or thelike) can be added to the pressure-sensitive adhesive to reduce thetenacity of the bond to the underlying second structure 42, ifnecessary, so that the pressure-sensitive adhesive readily detaches fromthe second structure on opening (particularly on the very firstopening).

The pattern 22 of pressure-sensitive adhesive, as noted, is applied tothe first structure 10 at regular intervals along the first structure.The spacing or index distance d between the patterns 22 can correspondto a dimension, such as a length, of packages to be produced from thepackaging laminate.

The adhesive application station 18 can comprise any suitable devicecapable of accurately applying the pressure-sensitive adhesive to thefirst structure in the desired pattern 22, at regular intervals alongthe structure. For example, as shown, the adhesive application stationcan comprise a gravure roll 24 that picks up the pressure-sensitiveadhesive from a reservoir 26 on the outer surface of the roll such thatthe adhesive fills one or more recessed areas in the surface. A doctorblade 28 scrapes off excess adhesive so that it remains essentially onlyin the recessed area(s). The first structure 10 is contacted by thegravure roll; a backing roll 30 provides support on the opposite side ofthe first structure.

After application of the pressure-sensitive adhesive, the firststructure is advanced to a dryer 31 such as an oven or the like, to drythe pressure-sensitive adhesive. The first structure is then advanced toa second adhesive application station 32 at which a permanent laminatingadhesive 34 (FIG. 1b ) is applied to the first structure in such amanner that a sufficiently large proportion of the surface is covered bythe permanent adhesive to permit the first structure to be adhesivelyattached to a second structure at a downstream laminating station 40.The permanent adhesive 34 does not cover the pressure-sensitive adhesive20. Furthermore, when the pattern of pressure-sensitive adhesiveincludes an adhesive-free region 23 to form a thumb tab or graspingportion as previously noted, the pattern of the permanent adhesive alsodoes not cover the adhesive-free region 23. Thus, the permanent adhesivemust be applied by an apparatus capable of accurately applying theadhesive in a predetermined pattern, in registration with thepressure-sensitive adhesive but not covering it or the adhesive-freeregion if present. A suitable adhesive application device 32, as shown,can be a gravure roll of the type previously described.

The permanent adhesive 34 can comprise various compositions. Suitableexamples include two-component polyurethane adhesive systems, such asTycel 7900/7283 available from Henkel.

As noted, after the application of the permanent adhesive, the firststructure is advanced to a dryer 33 such as an oven or the like. Thefirst structure is then advanced to a laminating station 40, comprisinga pair of rolls forming a nip therebetween. The first structure 10 ispassed through the nip along with a second structure 42 that is advancedfrom its own supply roll 44, and the first and second structures arelaminated to each other. The second structure comprises one or morelayers of flexible material, and is coextensive with the firststructure—i.e., the width of the second structure is substantially equalto the width of the first structure and the longitudinal edges of thesecond structure substantially coincide with the longitudinal edges ofthe first structure. The resulting laminate 46 is then advanced to areel-up (not shown) where it is wound into a roll for subsequentprocessing in the second phase of the manufacturing process as describedbelow. Alternatively, it is possible for the reel-up operation to beomitted, such that the laminate is directly advanced to the secondphase.

With reference to FIGS. 2 and 6, the second phase of the process is nowdescribed. A supply roll 48 of the laminate 46 formed in the first phaseof the process is shown. The laminate is advanced from the supply rollto a first scoring station 50 at which a first score line 52 (FIG. 6) isformed through the thickness of the first structure 10. The first scoreline 52 is in registration with (i.e., coincides with) the outerperimeter 22 a (FIG. 1a ) of the strip-shaped pattern 22 ofpressure-sensitive adhesive 20. The first score line 52 extendssubstantially through the thickness of the first structure 10, butpreferably does not extend to any substantial extent into the secondstructure 42, as illustrated in FIG. 6.

The first scoring station 50 can comprise a laser 54 as depicted in FIG.2. The use of lasers for scoring through flexible materials is generallyknown, for example as described in U.S. Pat. No. 5,158,499, incorporatedherein by reference. The depth of the score line formed by the laser canbe regulated by regulating the power output or beam intensity of thelaser beam, the width or spot size of the laser beam, and the amount oftime a given spot on the film surface is irradiated by the beam. Thesefactors generally are selected based on the characteristics of thematerial being scored. Some materials are more readily scored by lasersthan other materials, as known in the art.

As noted, the first score line 52 must be in registration with the outerperimeter 22 a of the pressure-sensitive adhesive strip (and the outerperimeter of the thumb tab 23, if present). To accomplish thisregistration, the operation of the laser 54 is controlled to besynchronized with the advancement of the laminate 46. A sensor 56disposed adjacent the laminate 46 can be used for detecting a feature onthe laminate whose location in relation to the strip ofpressure-sensitive adhesive is known, and the sensor's output signal canbe used by a suitable controller (not shown) for controlling the laser54.

Next, the laminate is advanced to a second scoring station 60 at which asecond score line 62 (FIG. 6) is formed through the thickness of thesecond structure 42. The second score line 62 is in registration with(i.e., coincides with) the inner perimeter 22 b (FIG. la) of thestrip-shaped pattern 22 of pressure-sensitive adhesive 20. The secondscore line 62 extends substantially through the thickness of the secondstructure 42, but preferably does not extend to any substantial extentinto the first structure 10, as illustrated in FIG. 6.

The second scoring station 60 can comprise a laser 64. The operation ofthe laser 64 is synchronized with the advancement of the laminate in amanner as described above. A sensor 66 can detect a feature, such as aneye mark, on the laminate whose location in relation to thepressure-sensitive adhesive strip is known, and the sensor output can beused for regulating the laser operation so that the second score line isin registration with the inner perimeter of the pressure-sensitiveadhesive strip.

As an alternative to the use of lasers for scoring the laminate, thescore lines 52, 62 can be formed in the laminate by mechanical scoringor cutting. For instance, as depicted in FIG. 3, a first scoring station50′ can comprise a kiss roll 51 and backing roll 53 that form a nipthrough which the laminate is passed. The kiss roll 51 comprises arotary cutting die defining a cutting edge (not shown). The kiss rollacts in conjunction with the backing roll to cut partially through thethickness of the laminate starting from the outer surface of the firststructure 10, such that the first structure is substantially scoredthrough while the second structure is left intact. The second scoringstation 60′ likewise comprises a kiss roll 61 and backing roll 63 forscoring through the second structure 42.

Additionally, it is within the scope of the invention to laser-score oneside of the laminate and to kiss cut or otherwise mechanically score theother side. This can be advantageous, for example, when one of thestructures making up the laminate is readily scored by a laser but theother structure is not. For instance, when the first structure 10 is apolyester such as PET, it can readily be scored with a laser, but if apolyethylene heat seal layer is employed on the opposite side, laserscoring may not be the best choice because polyethylene does not scorewell with a laser. In this case, kiss cutting or other mechanicalscoring can be used to score the inner structure 42.

After the scoring operations, the laminate 46 can be sent to a reel-up(not shown) and wound into a roll for subsequent processing. Thelaminate can also be slit into a plurality of partial widths and woundinto multiple rolls. In this latter instance, each partial width wouldhave the recurring patterns of pressure-sensitive and permanentadhesives applied with suitably configured adhesive applicators to thefull-width material, and would have the recurring score lines formed bysuitably configured scoring devices acting on either the full-widthlaminate prior to slitting or acting on each partial-width portion afterslitting.

An advantage of the invention, versus the formation of a web havingdiscrete labels applied to a partial portion of the web surface as inthe prior art, is that the laminate has a uniform thickness throughout(because the first and second structures are coextensive) and thereforewinds well into good-quality rolls. In contrast, a web with labelscentrally located in the width of the web tends to produce wound rollsthat are soft in the radial direction at the two ends of the roll wherethe labels are not present. Additionally, the web with labels is muchthicker than laminates made in accordance with the invention, and hencethe laminates of the invention can achieve a greater square footage perroll of a given diameter. As already noted, a further drawback to theuse of labels is the necessity of applying the labels to the web in an“off-line” process, which often entails shipping a roll of the web to aconverter that applies the labels and then ships the roll back to thepackage manufacturer. In the process of the invention, the manufactureof the laminate and the incorporation of the opening and reclosefeatures in the laminate are conducted in an in-line fashion as part ofthe same overall process. The process of the invention thus is much moreefficient and less costly.

Additionally, the invention avoids other drawbacks associated with theuse of labels. More specifically, pressure-sensitive adhesive labelstypically require a release liner that is peeled off and thrown away,which represents waste. Furthermore, there is the additional waste ofthe skeleton material left over after die-cutting the labels from thelabel web material. The present invention eliminates such waste andattendant costs.

Some possible applications for the resulting laminate are now explainedwith reference to FIGS. 4-9. FIGS. 4 and 5 show a flexible package 70.The package includes an outer wrapper 74 that envelopes the packagecontents and is sealed to enclose the contents. The outer wrapper 74comprises a packaging laminate made by a method in accordance with theinvention, such as the laminate 46 previously described. The outerwrapper is manipulated into a tubular shape and the longitudinal edgesof the wrapper are sealed together by a suitable sealant material toform a longitudinal seal (not shown), typically adjacent the bottomsurface of the package. The opposing portions of the wrapper are sealedtogether along transverse seal lines 76, 78 adjacent the opposite endsof the tubular wrapper. The ends of the wrapper can be gusseted ifdesired, as known in the art.

In the illustrated package, the portion of the outer wrapper 74 havingthe score lines 52, 62 is provided to be on the top surface of thepackage. The area of the wrapper bounded by the score lines canconstitute any fraction of the total top surface of the package, butadvantageously the area is a majority of the total surface area of thetop surface.

Based on the previous description of the laminate 46 and its formationprocess, it will be appreciated that the presence of the score lines 52,62 has little or no impact on the barrier function of the outer wrapperbecause each score line extends only partially through the totalthickness of the wrapper and the score lines are not aligned with eachother. Additionally, the pressure-sensitive adhesive 20 fills the spacebetween the score lines so that even if the score lines overlap somewhatin the thickness direction, there is still no open route between them.Furthermore, the score lines typically have a small width, on the orderof a few thousandths of an inch.

Various materials can be used for the construction of the outer wrapper74. With reference to FIG. 6, in the illustrated embodiment, the firststructure 10 that forms the outer surface of the wrapper comprises asingle layer 80 of flexible material. The layer 80 can comprise variousmaterials. A preferred material is a polyester such as polyethyleneterephthalate (PET). As noted, the PET layer can be reverse-printed ifdesired, although alternatively it can be printed on its exterior andcovered by an over-lacquer (not shown). The second structure 42 formingthe inner surface of the wrapper comprises a barrier layer 82 and asealant layer 84. The sealant layer 84 constitutes the innermost surfaceof the wrapper, and can comprise various sealant materials such as heatseals or cold seals. Heat seals generally are preferred because theyprovide stronger seals than cold seals typically are capable ofachieving. Any suitable heat seal materials can be employed, such aspolyethylene, polypropylene, ionomer resins such as SURLYN®, or others.

The barrier layer 82 can comprise any of various barrier materialsincluding barrier polymer films such as: ethylene vinyl alcoholcopolymer (EVOH), polyamide, and the like; metallized polyolefin filmssuch as polyethylene, polypropylene, oriented polypropylene, and thelike; AlOx-coated polymer films; SiOx-coated polymer films; metal foil;and others.

The barrier layer 82 and sealant layer 84 can be joined in various ways,including adhesive lamination, extrusion lamination, or coextrusion.

Advantageously, the laminate includes a metallization layer or a metalfoil layer between the first structure 10 and the second structure 42,for example by providing a metallization layer 85 on the surface of thelayer 82 that faces the first structure 10. This is beneficial inenhancing the barrier performance of the laminate as already noted.Additionally, however, the metallization layer or metal foil layer canalso be helpful when a laser is used for scoring the second structure42. In particular, when the sealant layer 84 comprises polyethylene,which is not as readily scored by laser as some other materials such aspolyester, it can be difficult to employ a sufficiently high laserenergy to score through the polyethylene sealant layer without scoringthrough the laminate more deeply than desired. In some cases, the entirethickness of the laminate may be scored through, which is undesirable.The metallization layer or metal foil layer can be helpful in “tuning”the laser to penetrate only up to the metallization layer or foil layer.

The function of the opening and reclose feature provided by thepattern-applied adhesives and the score lines will now be described.With reference to FIGS. 4 and 6, the package 70 is shown in a closedcondition, for example as initially filled and sealed in a packagingplant. On the top surface of the outer wrapper 74, the first or outerstructure 10 is adhesively joined to the second or inner structure 42via the permanent adhesive 34. The outer score line 52 bounds an outeropening portion 86 of the outer structure 10. In this embodiment, theouter opening portion 86 has a generally U-shaped perimeter having threesides defined by the score line 52, and is attached to the remainder ofthe outer wrapper along a fourth side (i.e., an imaginary line extendingbetween the free ends of the two legs of the U-shaped score line 52).The inner score line 62 is also generally U-shaped and parallel to theouter score line, but is spaced inwardly of the outer score line so asto define an inner opening portion 88 of smaller area than the outeropening portion 86. Accordingly, there is a marginal region 90 of theouter opening portion 86 that extends beyond the edge of the inneropening portion 88. The pressure-sensitive adhesive 20 is disposedbetween this marginal region 90 and an underlying surface 92 of theinner structure 42. The outer opening portion 86 and inner openingportion 88 are permanently joined by the permanent adhesive 34.

Consequently, when the outer opening portion 86 is detached from theouter wrapper along the outer score line 52 and is peeled back as inFIG. 5, the inner opening portion 88 remains affixed to the outeropening portion and comes with it, thereby creating an opening 94 in thetop surface of the outer wrapper 74 as defined by the inner score line62. The outer and inner opening portions essentially form a flap thatremains attached along a hinge line defined between the free ends of thetwo legs of the U-shaped score lines.

The outer structure 10 preferably has a greater affinity for bondingwith the pressure-sensitive adhesive 20 than does the surface 92 of theinner structure 42, and hence the pressure-sensitive adhesive 20 isdetached from the surface 92 and remains attached to the marginal region90 of the outer opening portion 86 as shown in FIGS. 5 and 7. Thepackage is reclosable by re-attaching the pressure-sensitive adhesive 20to the surface 92 of the inner structure 42 to restore the package tothe condition shown in FIG. 6.

The greater bonding affinity of the outer structure 10 can be achievedin various ways. When the outer structure comprises a layer of PET andthe layer 82 of the inner structure to which the pressure-sensitiveadhesive is attached comprises a polyolefin such as polypropylene,oriented polypropylene, or metallized oriented polypropylene, the PETwill naturally have a greater affinity for bonding to the adhesive thanwill the polyolefin layer. Additionally or alternatively, the surface ofthe outer structure 10 can be treated, as previously noted, by coronadischarge or flame treatment, to increase the surface energy and enhancethe bonding affinity. It is also possible, as already noted, to controlthe bond strength of the pressure-sensitive adhesive to the layer 82 byincluding an additive in the adhesive to reduce the bond strength, ifdesired.

Although it is preferred to have the pressure-sensitive adhesive beapplied to the outer structure and to remain on the outer structure uponopening, it is also within the scope of the invention to apply thepressure-sensitive adhesive to the inner structure and to remain on theinner structure upon opening. This is less preferred, however, becauseof the greater tendency for crumbs or the like from the containedproducts to become adhered to the pressure-sensitive adhesive andthereby reduce its adhesiveness with repeated openings and reclosings.It is believed that this tendency is reduced when the pressure-sensitiveadhesive remains with the outer structure, since it is out of the way ofthe package opening when products are being removed.

It will be appreciated from the above description that laminates made inaccordance with the invention inherently provide a tamper-evidencefunction for a package because after opening it is very difficult orimpossible to replace the opening portions 86, 88 in such a way as toachieve a completely smooth, flush condition with the surroundingportion of the laminate. It tends to be readily ascertainable that thepackage has been opened. When printing is included on the laminate, itis even more noticeable when the package has been opened because it isdifficult to achieve perfect registration of the printed matter acrossthe score line when reclosing the package.

Additionally, other tamper-evidence features can be incorporated intothe packaging structure. For example, when the outer structure isreverse-printed with ink, an area on the marginal region of the outeropening portion can first be treated (such as by applying a releasecoating or the like) to reduce the adherence of the ink so that when thepackage is first opened, the ink on the area of the marginal regiondetaches from the marginal region of the outer opening portion andremains with the pressure-sensitive adhesive on the inner structureadjacent the package opening. The release coating can be applied in apattern (e.g., spelling out a word such as “Opened” or the like). Othertypes of tamper-evidence features can be included.

The laminates made in accordance with the invention can be used forforming other types of packages such as stand-up pouches or pillowpackages. For instance, FIG. 8 shows a stand-up pouch 100 constructedfrom the laminate 46 as described above. The outer score line 52 andinner score line 62 are formed in a side wall of the pouch. The openingand reclose feature operates in a manner similar to that describedabove. An alternative form of thumb “tab” 23′ is included, wherein acorner portion of the outer flap delineated by the outer score line 52is left free of pressure-sensitive adhesive.

It should be noted that the terms “line of weakness” and “score line” asused herein refer either to a complete cutting through of one or morelayers of the laminate or to a weakening of such layer(s) allowing thelayer(s) to be severed along the score line.

The packages described above are formed by completely enveloping thecontents in the flexible laminate. Alternatively, however, it is withinthe scope of the invention to employ the flexible laminate as a liddingstock for forming flexible lids that can be secured (e.g., byheat-sealing or the like) to a flange of a tray or other container thatcontains the contents. In this manner, the lid includes a built-inopening and reclose feature as previously described. For instance, FIG.9 shows a package 110 comprising a container body 112 having a side wall114 and a flange 116 extending from the upper edge of the side wall. Thecontainer body 112 can comprise various materials (e.g., polymer, paper,foil, etc.) and can be formed by various methods (e.g., thermoforming,molding, etc.). The open top of the container body is closed by a lid118 formed of a flexible laminate 46 in accordance with the invention.The lid is sealed to the flange 116 by any suitable technique, such thatthe lid is firmly attached to the flange. The lid includes an openingand reclose feature formed by an inner score line 62 and an outer scoreline 52 and pressure-sensitive adhesive 20, as previously described. Thepackage 110 also includes a thumb “tab” 23′ generally as described inconnection with FIG. 8; alternatively, a thumb tab of the type shown inFIGS. 4 and 5 can be used.

Example

A polyethylene terephthalate (PET) film was printed in a rotogravurepress with a layer of red ink, and then was printed with a layer ofwhite ink over the red ink, the ink layers covering one entire side ofthe film. Next, the ink side of the film was printed with apressure-sensitive adhesive in a U-shaped pattern. The adhesivecomprised a water-based acrylic formulation. Finally, a permanentsolvent-based urethane adhesive was pattern-applied to the film outsideof the U-shaped pattern. A 1-mil thick metallized oriented polypropylenefilm was laminated in-line to the PET film to form a 2-ply structure. Anumber of such laminates were produced. After two days of cure time, oneof the laminate samples was laser-scored on the top (outer) and bottom(inner) plies generally as previously described; one sample waslaser-scored on the top ply and mechanically die-cut on the bottom ply;a third sample was die-cut on both top and bottom plies. The sampleswere tested to assess their opening and resealing performance.

The sample having both top and bottom layers laser-scored had a maximumpeel force to open the flap of 850 grams. By comparison, the sample thatwas laser-scored on top and die-cut on bottom had a peel force of 789grams. The sample that was die-cut on top and bottom had a peel force of815 grams. All samples had acceptable reseal performance.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A resealable packaging structure for housingproducts and allowing access to the products through a repeatedlyopenable and closeable flexible structure and wherein the openable andcloseable flexible structure comprises a. a laminate comprising an outerlayer and an inner layer that are coextensive across substantially theirentire areas, each of the layers having an upper surface and a lowersurface and wherein the outer layer lower surface is adhered to theinner layer upper surface, the laminate comprising a permanently adheredportion and a releasably adhered portion; b. a first opening in thelaminate defined by an outer layer opening portion and a second openingin the laminate defined by an inner layer opening portion wherein theouter layer opening portion is larger in area than the inner layeropening portion and extends beyond the periphery of the inner layeropening portion; c. a non-detachable flap having a releaseable perimeterthat is resealable to the inner layer upper surface, the flap comprisingthe outer layer opening portion and the inner layer opening portion andwherein the inner layer opening portion of the flap has dimensions atleast equal to the dimensions of the second laminate opening and whereinthe outer layer opening portion of the flap has dimensions at leastequal to the dimensions of the first laminate opening; d. the innerlayer upper surface comprising a first marginal region in the releasablyadhered portion of the laminate and surrounding the second laminateopening; e. the outer layer lower surface comprising a second marginalregion in the releasably adhered portion of the laminate and carried onat least a portion of the periphery of the outer layer lower surface;and f. the first marginal region being releasably adhered to the secondmarginal region so that the flap may be repeatedly opened to allowaccess to the products housed within the resealable packaging structureby releasing the first and second marginal regions and repeatedly closedto prevent access to and exposure of the products by sealing the firstand second marginal regions.
 2. The resealable packaging structure ofclaim 1 wherein the inner layer opening portion of the flap hasdimensions at equal to the dimensions of the second laminate opening. 3.The resealable packaging structure of claim 1 wherein the outer layeropening portion of the flap has dimensions greater than the dimensionsof the second laminate opening.
 4. The resealable packaging structure ofclaim 3 wherein the outer layer opening portion of the flap comprises atab portion that extends beyond the first and second marginal regionsand is not adhered to the inner layer upper surface.
 5. The resealablepackaging structure of claim 1 wherein the laminate comprises a portionthat is unadhered.
 6. The resealable packaging structure of claim 1wherein the repeatedly openable and closeable flexible structure is alidding for a tray.
 7. The resealable packaging structure of claim 1wherein the permanently adhered portion of the laminate comprises apermanent adhesive.
 8. The resealable packaging structure of claim 1wherein the releasably adhered portion comprises a pressure-sensitiveadhesive.
 9. The resealable packaging structure of claim 1 wherein theouter layer and inner layer are coextruded.
 10. The resealable packagingstructure of claim 9 wherein the outer layer and inner layer areadhesively laminated together.
 11. The resealable packaging structure ofclaim 9 wherein the outer layer and inner layer are polymerically bondedtogether.
 12. The resealable packaging structure of claim 1 furthercomprising an adhesive label applied to the flexible structure.
 13. Theresealable packaging structure of claim 1 wherein the repeatedlyopenable and closeable flexible structure is located on the flange of atray.
 14. The resealable packaging structure of claim 1 wherein theflap, the inner layer opening portion, and the outer layer openingportion are created by scoring the inner layer and the outer layer. 15.The resealable packaging structure of claim 1 wherein the inner layer isscored only through a portion thereof
 16. The resealable packagingstructure of claim 1 wherein the outer layer is scored only through aportion thereof
 17. The resealable packaging structure of claim 1wherein the flap, the inner layer opening portion, and the outer layeropening portion are created by cutting the laminate.
 18. The resealablepackaging structure of claim 1 wherein the first marginal region and thesecond marginal region are in the form of a partial racetrack design.